Liquid fuel burning apparatus



v20, 1949' M. A. PowERs ETAL LIQUID FUEL BURNING APPARATUS 1 Filed May27, 1941 3 Shets-Sheet 1 Orig' Milton Power.: /Ycl Jutteield' Original-Fled I ay 27, 1941 DGZ-O, 1.949 M. A. POWERS HAL 2,491Q517 LIQUID FUELBURNING APPARATUS 's sheets-sheet 2 l|| gnam )filtern A. Riu/ers Mez/flqrfefffezd De 20, 1949 M. A. PowERs ETAL LIQUID FUEL BURNINGAPPARATUS s sheets-'sheep s Original Filed May 27, 1941 lll- .Wwfm/ 7.P@ A AH. 4

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Patented Dec. 20, 1949 LIQUID FUEL'BURNING APPARATUS Milton A. Powersand Noel H. Sutterfield, Detroit, Mich., assgnors to The Timken-DetroitAxle Company, Detroit, Mich., a corporation of Ohio Qrginal applicationMay 27, 1941, Serial No. 395,464. Divided and this application July 17,1944, Serial No. 545,234

Claims.

This invention relates to oil burning apparatus of the rotary wall flametype, and more particularly to water heaters of small capacity forsmaller homes embodying oil burners of the general type shown in UnitedStates Letters Patent to Sutteriield No. 2,102,763 and to Wilson andSutterfield No. 2,310,333, and is a. division of our application SerialNo. 395,464 led May 27, 1941, which issued October 24, 1944, as UnitedStates Letters Patent No. 2,360,891.

We have discovered that by employing a fan having adequate volumetriccapacity to support combustionbut delivering air at suflicientlyrestricted velocity to insure emcient ingition, and at the same timeavoiding excessivel recirculation, in combination with a grill assemblydesigned to deflect the name behind the flame rim, and a flame shield toprevent the combustion gases from making direct contact with the coldportion of the water backed surfaces, it is possible to successfully usesmaller diametered hearths and to eiliciently burn fuel at lower ratesthan have heretofore been considered feasible with a rotary wall flametype burner.

It is accordingly the primary object of our invention to provide a smallnovel oil burning water heating apparatus capable of eiiiciently burningextremely small quantities of oil, thereby to make it practical formedium sized and small homes having limited space and money for suchfacilities.

A further object of our invention is to provide aheating unit embodyingan oil burner of the rotary wall name type in which the hearth andcombustion chamber are completely suspended in the cabinet member andeiciently insulated against heat loss.

A further object of our invention is to provide a fan or airdistributing device having sufficient capacity to eiliciently pump therequired amount of air for combustion and which is so designed as toavoid imparting suflicient velocity to the air to interfere withignition, even when an extremely small hearth is used, and at the sametime is also designed to avoid excessively recir-v culating hot gases ofcombustion.' j

A further object isto providel a small rotary wall name type waterheating oil burner with a 'novel hearth name rim, grille and shieldassembly which makes it possible to efliciently utilize smaller diameterand/or capacity combustion chambers than have been heretofore regardedas practicable.

A still further object is to provide improve-` ments in oil burnercontrols of the trip-bucket type, which eliminate the inconvenience ofun. necessary trippings, and still insure safety of control, and to alsoprovide improved means for. tiltitng the hearth surface toward theoverflow; por y,

Further objects are to generally improve and refine certain subordinatefeatures of heating apparatus, which will become apparent as thespecification proceeds in conjunction with the annexed drawings, andfrom the appended claims.

In the drawings:

Figure 1 is a vertical sectional view of a heating apparatus embodyingthe invention.

Figure 2 is a vertical sectional 4view on an enlarged scale of the lowerpart of theapparatus shown in Figure 1, and illustrates the hearth anddistributor assembly.

Figure 2a is a fragmental elevational view of the ignitor shown inFigure 2, as it appears when viewed from the right-hand side of thatfigure.

Figure 3 is a fragmental top plan view of the hearth and distributorassembly shown in Fig-- ure 2.

Figure 4 is a bottom plan view of the fan shown in Figures 2 and 3, andillustrates the relationship assumed by the oil flinger tubes with re.spect to the fan blades.

Figure 5 is a Sectional view of the lower part of the casing shown inFigure l, taken substantially along the line 5-5 of that figure.

Figure 6 is a view similar to Figure 2, but illustrates a modified formof hearth assembly, also forming part of the invention.

Figure 'I is a fragmental sectional view on a greatly enlarged scale, ofthe edge of the overflow port shown in Figure 6.

With continued reference to the drawings, wherein like referencecharacters have been em ployed to designate like parts throughout theseveral views thereof, the heating apparatus of the invention comprisesa cabinet member A, in which is suspended a shell-like combustionchamber B and also a hearth assembly C, which in turn supports a liquidfuel burning apparatus designated generally as D.

Cabinet structure The cabinet structure is made up of a base member I0having a bottom rim I I, and adjacent its upper edge are provided a.plurality of circumferentially spaced brackets I2. The cabinet structureproper, designated as I3, is telescoped within base member I 0 at itsllower edge and rests upon brackets I2. The partsl may be secured ln 3overlapped assembled relationship by nut bolt assemblies I4.

The lower front portion of the cabinet is provided with a serviceopening I5, which is closed by a door I6 having a handle Il in the formof a knurled headed bolt threaded into a nut welded to the inner face ofthe casing. Each side of the door, at its lower edge, is provided with aclip member I8, which ts inside base member I0, and the latter isprovided with a single upstanding re.- taining member I9, locatedadjacent the middle of the door, which prevents the mid-portion of thedoor from bowing inwardly, when it is disposed in the abuttingrelationship to the upper edge of member I shown in Figure l.

The base is also preferably provided with a plu: rality of levellingscrews threaded into brackets 2| secured to the inner wall of the baseand locked in place by lock nuts 22.

Cabinetl I3 has a plurality of brackets 24 for supporting the base plateand the combustion chamber, as hereinafter set forth in detail, whichare secured at circumferentially spaced points around the interior ofthe cabinet structure, and

a bracket 23 for supporting a transformer T, all

fwhich are attached as by spot welding. A plate 24 is secured to thetransformer and is hooked under a lip provided on bracket 23. The plateand bracket are secured together at their lower edges by bolts 25.Although the cabinet has been illustrated as a circular section, it isto be understood that it may be of rectangular or other shape in sectionwithout departing from the spirit of the invention.

'The top of the cabinet is closed by means of a member 26 having a ange2 tting tightly over the upper edge of the cabinet. A plate 28,terminating inwardly of ange 2l, is secured in spaced relationship tothe under side of closure 26 by means of a plurality of brackets 29, andthe space between the two members is filled with a blanket of insulatingmaterial 3I of any suitable character.

The cabinet top also embodies a combined baille and inspection assemblyof novel form. -Supported in spaced relationship below the top, by meansof a plurality of brackets 3B, is a baffle 30a, which is operable todivert the hot products 0f combustion around the upper convolutions ofthe coil, and prevent escape to the flue until they have transmittedsubstantially all of the available heat to the coil, as will hereinafterappear.

The baille is provided with a preferably eccentrically locatedinspection opening 30h of restricted size, while cover 2Q is providedwith a concentrically located inspection opening 32, closed by a hingedcover 33 or the like. By opening cover 33 the operation of the burnermay be observed through openings 33h and 32, and beeause of the locationof opening 32 this may be tiene without permitting excess air to enternear therese ei the flegie end interfere with eeeieee'- iiel.- Alea be.eee ef the eeeeilirieiiy ef epeelag Sie., the eier he reteneseeee'tefefegrss'vely bring the entire hearth view, the eld of vision forone position cftle cover being indicated by dotted lines' in Figure l.

The reer- Well, 9- tlie eebinet edieeegt. the iep' is provided with ailueA pipe opening 34, which extends completely to the upper edge oi thecabinet, sq that when the top is removed it presents an openfsidedrecess.v The back of the cabinet is also provided. with e Deir efOpenings en d 35., through whieetre outlet end inlet eegeeeiieae fluepipe (not shown) in well knpwn manner.

respectively of the coil project, as will hereinafter appear.

Combustion chamber assembly The combustion chamber proper comprises acylindrical shell 4I of sheet metal having its endsbutted at 42 andsecured together in any suitable manner such as by welding. Thecombustion chamber fits within the'cabinet and is so diametered as toprovide a space 43 between the walls thereof, and which is preferablycompletely filled with a blanket of insulating material 44.

Secured to the outs-ide of the combustion chamber adjacent its lowerend, as by welding or the like, are a plurality of bracket members 45which are preferably so spaced as to seat upon every other bracket 24',although it is to be understood that if desired they may be made equalin number t'o, and seat upon, all of brackets 24'. Brackets 45 aresecured in place on brackets 24 by a plurality of screws 46 and nuts 4l.A hearth assembly is also supported upon screws gli as in a marmer eo behereinafter deserted.

Ae eeen in .Finire lfplete 'everless the weer edge ef eembueiien'ehember .4!! bei termizites short of the walls of cabinet I3, so thatthe insulation the top o f olpsureV 'member 25 may contact directly withthe insulation 4,4 between the cabinet and the combustion chamber walls.To insure proper spacing of 'the combustign chamber from the walls ofthe cabinet a plurality of spacer members 491' are preierably secured tothe. eembueen ehember and t eleeely es eiget the cabinet Walls tomaintain the partsv in proper:

L ly spaced relationship.

Disposed. "Wthir'i' 1combusti@ .chamber 4!! in. proximity to theinternal wall thereof, is a cylin: drical helically wound water heatinggoil 5 0, pref,- erably of copper,'and is supported in fixed rela:v tionthereto by means of an inlet fitting 5I and an utlet fitting 52, both ofwhich are secured to the combustion 'chamber as by cap screws 5,5. Asseen in Figure 1, each tting is proyided with short neck 54 whichprojects through an opening in the combustion chamber and to which isthreadedly secured a pipe nipple 55, The latter are connected to thedomestic hot water or heating radiator lines in Well known manner.

An opening 56 is provided adjacent the` top of the combustion chamberand secured in alignment therewith, is a flanged nue connecting member5T, by a pair of nut and bOlt assemblies 58. Flue connection 51 extendsthrough the insulation and opening 34 out of the cabinet to a usual Inassembling, the chamber may be lowered as a unit into the cabinet withmember 5,1 in place, by reason of the shape of opening 34, after whichthe connections which maintain the combustion chamber in place areconnected.

Hearth structure The entire hearth assembly is carried ln novel mannerVby a feundation er base plate 6l, which hee e demeter slightly greaterthan, the eembe.- tien ehember, eed ie eleerreferebly eiiiieer'eed erbreekeie 45. Altrieueh if'fde eef @my e ev'v brackets 2 4" maybeutilized for lsupporting the combustion chamber and hearth assembly,pref-- erably all of the boltsl 46 extend through open-f ings in thebase plate 6I, and nuts' S2 are threaded thereon to hold the base platein place.

A layer of insulating material B4 is mounted on the baseplate, end whennuts $2, are turned tiene the reeherel esse' ef' tae'leeuletien @l isclamped in air-tight engagement with the lower edge of the combustionchamber. Base plate 6| may be either embossed so that the hearth,supported thereby by supports 1| of equal length, will incline from thehorizontal, or the lower edge of the combustion chamber may be so shapedas to lie in a plane inclined to the horizontal, so that when the baseplate is pulled into assembled relationship it will assume a similarinclination. Either alternative eliminates the necessity for speciallydesigning the hearth to drain any overflow oil to one side. In theconstruction shown in Figure 1 the entire base plate is inclined byreason of an inclined edge provided on chamber 4|.

As seen in Figure 2, the base plate is approximately centrallyapertured. Disposed in alignment therewith is a spacer collar B6 whichsupports the central portion of an apertured metal hearth 61 in spacedrelation to the base plate. The hearth and collar are secured to thebase plate by a sleeve 68 which is iiangedover the hearth and base plateat its upper and lower ends respectively. The outer edge of the hearthis provided with an upstanding iiange 69, to which is secured aplurality of supporting legs 1|, which extend through openings |2 in theinsulation and rest upon the upper surface of the base plate, to whichthey are attached as by welding.

Mounted in spaced relation to each other on the hearth is an annularflame rim having an oil atomizing and vaporizing wall 13 and an airdeflecting wall 14, which are welded to a plurality of U-shaped brackets15, and the latter are welded to the hearth, so as to form a rigidunitary assembly. Also rigidly secured to the hearth is a shield ring16, which snugly fits inside flange |59 and may be welded thereto ifdesired.

At one side of the hearth is provided an igniter of novel construction,comprising an electrode 11, having an outwardly projecting portion 11a,which is disposed in sparking relationship to the inner face of wall 13,and is disposed at a predetermined angle with respect to a radius drawnthrough the center of the hearth, preferably degrees, as indicated inFigure 3. The electrode is eccentrically mounted in an insulator 18 ofgenerally cylindrical form. The latter is frictionally gripped in abracket 18a carried by the base plate. The hearth adjacent the insulator18 is flanged up as at 19 to prevent any excess oil from leaking downbetween the insulator and hearth.

By mounting the electrode in an igniter insulator having an eccentricaperture, and mounting the insulator for rotative adjustment, a fixedangle of incidence and a predetermined gap may be maintained despitemanufacturing tolerances and burning or wear. For instance, if the gapbecomes too large, insulator 18 may be rotated slightly in its bracket,to move the electrode closer toward wall 13. If this results in swingingportion 11a materially away from the desired angle, proper relationshipof the parts may be restored by loosening a pair of nuts 19a androtating the electrode within a clip 191:, which engages flat portionsprovided on opposite sides of the insulator. When the adjustment iscompleted, nuts 19a are then tightened, which pulls the clip into tightengagement with a shoulder 19e provided on the electrode.

The igniter is connected to the high tensioncircuit of the transformerin any well known manner. Located at the low side of the hearth,prefeably opposite the ignite?, is a.v pair of recesses.

or circular channels and 8| which surround an outlet port 82. Outletport 82 communicates with a pipe 83 supported by a bracket 84 below thehearth, which leads to a trip bucket type of automatic shut-offmechanism S so that after a predetermined quantity of oil passes throughpipe 83 the bucket will be tripped and the burner automatically shutoff. Mechanism S projects through an opening in the casing and ispreferably supported on a bracket assembly 84a carried by plate 6|Channels 80 and 8| perform the highly important function of trapping anyoil discharge which is not immediately ignited at the time the burnerstarts. This prevents a ilow of oil through pipe 83 into the trip bucketon cold start. As previously pointed out, the foundation plate isinclined, which produces a corresponding slope of the hearth towardoutlet 82, so that in the event of failure of the ignition, theoverflowing oil will pass through the discharge port into pipe 83, andcause the shut-ofi mechanism to stop the burner motor. In the past somediiiiculty has been experienced in having small driblets of oil on coldor slow starts dripping into the drip bucket and eventually tripping thebucket, despite the fact that no more than normally cold starts haveoccurred, and no occasion has arisen for the shut on of this character.

With the novelconstructions herein disclosed, any oil accumulating inchannels 80 and 8| during cold starts, and which is not immediatelyignited, is under normal conditions burned oi during the ensuing normaloperating cycle of the i burner, with the result that no oil whateverenters the trip bucket.

Grille structure A further important feature of the invention resides inan improved grille structure, which, particularly when employed incombination with the novel distributor of the invention and shield 16,greatly assists in enabling the burner to operate at extremely low ratesof oil consumption, and in combustion chambers of smaller size thanheretofore regarded practical.

The grille ring shown in Figures 2 and 3 comprises a simple cylindricalband of heat resistant sheet metal 85 having its ends overlapped andsecured together, and a plurality of similarly shaped channel members86. Each of the channel members is secured to or integral with the outerface of ring 85, preferably with the open sides of the channels facingdownwardly. As

r seen in Figure 3, the channels are disposed in symmetrical, radiatingrelationship to ring 85 and are supported approximately at theirmidportions by wall 13. Although the channels may be secured to theflame rim, the grille assembly preferably merely freely rests upon theame rim, so that any thermally induced expansion or contraction of theparts may take place freely. Also, it enables the grille ring to beinverted, so as to face the channels upwardly, depending upon thearrangement which is found to work best under the particular conditionat hand. The channels preferably open downwardly in the particular smallcapacity unit illustrated, so as to cause the flame to pass outwardlyalong thechannels and then behind wall 13, and to maintain azone ofrapid and eicient combustion between band 13 and shield 1S, and to alsomaintain the ilame rim at an eilicient fuel vaporizing temperature.Reversibility of the grille is particularly desirable 75 when the 'lowergrades of fueloil are burned.

The .function of any grille is to assist mixing ofthe -r and oilproccted from the distributor head and to prevent the haine from liftingabove the flame rim to a height where it will not heat the flame rimsuiicie'ntly to vaporize the oil projected against it. In the smallheating unit illustrated, the distance between the ends of thedistributor tubes, to be hereinafter described, and 'the flame rim iscomparatively short, approximately 21A; inches. With the rim in Asuchclose proximity to the flinger tubes it was found liinpossible for theolder type of grilles to properly mix lthe air and oil for complete andclean combustion without circulatinga large amount of the hot gases ofthe combustion. Excessive recircul- .lation is undesirable, especiallyin the small hot water heater because there may be many numerfA -ouscold starts, particularly during the summer season, and on a coldstart'the'eifect of excessive recirculation is to cause an excessiveilow of cold,

fresh air, which at high velocity may retardl rather than assistignition of the fuel. We have found that by so designing the fan as toproduce a'limited degree of recirculation, with suliicient volume tocombust the fuel and at suiiiciently low velocity to avoid delayingignition, as will be described hereinafter, and providing the grilleassembly constructed as just described, which d e fleets the gases ofthecombustion ame behind the flame rim under al1 normal conditions, andusing a shield 1 to prevent contact of the llame with the lower portionvof the coil, the apparatus performs with complete satisfaction.

Distributor The distributor comprises a motor and plumpv uting head 9 l.A pair of upwardly and outward? ly extending oil tubes 92, carried byhead 9| are designed to propel the oil in the form of unatomizeddroplets in a trajectory located above the blast from the fan, againstthe inner face of wall T3, with sufficient velocity to shatter oratomize them.

Secured to the upper end of shaft 89, by means of a set screw 93, is ahub member S, to which is welded a fan head or disc 9'5.

Secured to the underside of head 95 are a plurality of flanged blades 96and Sl, which are preferably equally spaced. Blades 96 are preferablysix in number and will be termed the pumping blades since they arecomparatively short and function primarily as pumping blades. Blades 91are two in number and extend beyond the periphery of the head and willbe hereinafter termed velocity blades,

It was found that the earlier designs of fans, having many long velocityblades, imparted too-- great velocity to lthe air, which rendered ignif,t'io'n, particularly on acold start, extremely :dif-1 ficult. Further,in a small combustion chamber and hearth assembly as employed in thepresent construction, a high air velocity tends Yto induce excessiverecirculation. The novel fan assembly just described overcomes thisdifficulty because the greater number of short pumping blades assuressufficient air for combustion v'vithout'r excess velocity, and bylocating the distributor tubes leeward of- 'the velocity-blades-'thub'sare maintains@ .out gf with the ,braise recirculated gases that aredrawn the fan and are discharged along the leading faces of the bladesAwith the fresh air supply.

To further insure against excessive recirculation by the tips of the oiltubes 92, and .to also protect the tubes against excessive heating,cover is provided with a short lip or skirt 38, and the ends of theflinger tubes are located closely ad.- jacent the fau'couer, Both ofthese features cooperate to prevent the recirculated gases from heatingand carbonizipg the oil ln the ends .of .the distributor tubes.

Shield 16 is important in the small sized illustrated, because in suchunit a number` o'kf critical factors are presen-t. .although shields `ofvarious types have -been before disclosed in the art the only functionswere to ,Prever-it the shielded parts from being subjected directly .tothe flame, and to prevent the cold water coils from chilling the flameand precipitating soot. It has been found that by making the shield L5of the correct height it will deflect the hot gases- Oi recrulatien andamenities uvwardlr'emi away from the lower convclutipns of the coil 53and very good control over the hearth terllpslaeA ture can bemaintained, addition to realizingthe decided advantage of preventingdirect con?. tact 0f the name W-itih the. 19H95 CQVQlilOQ 9? the coil.

The illustrated construction is e commercie! unit marketed by theassignee of this application and which has given complete satisfatiea inall fepecs.' The PPQr-*'ellt @.mligl .0i .th init are .as follows., whliare. Slifer; by War 0f ililutmw tion and not limitation. it heiligunderstood that some latitude is permissible, depending upon the size ofthe hearth, the speed of the fan and gther factors of the particularunit under consideration.

The hearth is approximately l0 inches in di ameter and shield 15 isspaced approximately 2 inches from wall 4I. Flame rim 'I3V is approxi-fmately 8 inches in diameter and one and one,- half inches high. whileshield 'I6 is three inches high. Grilles 86 are approximately one andonehalf inches wide and one-.fourth of an inch deep.

The fan is rotated at approximately 1600 R. P. M. The two sets of bladesare of the same width and their inner ends all terminate approximatelyfive-eighths of an inch from the axis of rotation. Blades 91 areapproximately one and seven?- eighths inches long, while blades 96 areapproxif mately three-fourths of an inch in length.

In Figures 6 and 7 we have. illustrated a mod-i ied form of heatingapparatus also formingpart of the invention. The major differencesreside in the use of an embossed base, which automatically disposes thehearth at the proper inclination to elect drainage of oil, and adifferent form of overliow port, which is particularly useful wherespace does not permit use of the double groove constructionshown inFigure 2.

A base plate Blais secured in tight engagement with the`lower edge ofthe combustion chamber as before.` Hwever, in this' Yinstance the loweredge lies substantially in a horizontal plane. and the plate,l inwardlyo f its clamping edges', is embossed or formed so as to present aninclined portion I0! to' which hearth supports 'Il are secured. Thisconstruction accordingly makes it possible to utilize a combustionchamber having a square lower edge and hearth suppgrtng legs of equallength, and yet supports th 'hearthA at the 'necessary inclination 't6eiect proper drainage of overflow oil. Also, if desired, insulationretaining members |02 may be secured to legs 1|.

In this form of the invention a single oil drainage groove |03 isprovided adjacent outlet 82a, and, as seen in Figure 7, the outlet ismachined out at |04 to provide a sharp edge |05 over which the oil mustdischarge. We have found that, when using commercial grades of number 2or number 3 fuel oil, the oil overiiowing over the hearth will build upin groove |03 and form a meniscus |05, as shown in Figure 7, to a depthof approximately one-sixteenth of an inch above edge |05 beforeoveriiowing into opening 82a. As previously explained, any oil remainingin groove |03 after the burner is started will be consumed during thenormal burning cycle, and the hearth will be dry when the burner is shutoif.

Accordingly, by using a sharp edge adjacent the outlet port, the oilwill build up to a depth suiiiciently great to take care of all normalconditions, and yet it is unnecessary to employ a high wall to impoundthe oil.

From the foregoing it is apparent that the invention provides waterheating apparatus of eilicient and extremely simple and durableconstruction; and which, by reason of the novel assembly, when top 26 isremoved, the interior of the cabinet and the combustion chamber arecompletely exposed, so that they may be inspected or serviced, and inthe case of Figure l, the entire coil may be thoroughly cleaned.

Also, by reason of the novel oil and air distributor, which suppliesadequate air for combustion and yet is designed to effect a minimumrecirculation of the combustion gases, in combination with novel grilleassembly which insures adequate combustion behind the wall 13, it ispossible to use a hearth and combustion chamber assembly of much smallerdiameter than has heretofore been regarded as practicable in a wall nameburner.

The invention may be embodied in other speciiic forms without departingfrom the spirit or essential characteristics thereof. The presentembodiments are therefore to be considered in all respects asillustrative and not restrictive, the scope of the invention beingindicated by the appended claims rather than by the foregoingdescription, and all changes which come within the meaning and range ofequivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by United States LettersPatent is:

l. In a liquid fuel burning apparatus having means defining a combustionchamber; a centrally apertured refractory hearth in said combustionchamber and having a fuel atomizing and vaporizing wall located adjacentits periphery against which oil and air are adapted to be projected by adistributing device located in the aperture in said hearth; meansproviding an outlet in said hearth adapted to be coupled to a burnershut-off mechanism; the upper surface of said hearth being so sloped asto cause liquid oil to drain along said hearth toward said outlet; andrecess means in said hearth surface adjacent said outlet foraccumulating a predetermined quantity of oil before flow to said shutoffmechanism occurs.

2. In a liquid fuel burning apparatus having means defining a combustionchamber; a centraily'apertured refractory hearth in said combustionchamber and having a fuel atomizing and vaporizing wall located adjacentits periphery against which oil and air are adapted to be projected by adistributing device located in the aperture in said hearth; meansdefining an outlet port opening upwardly into the oor of said hearth andadapted to be coupled to a burner shut-off mechanism, the upper surfaceof said hearth being so sloped as to cause any overflow oil to drainalong said hearth toward said outlet port; and means defining a recessin said hearth in surrounding relationship to said outlet port foraccumulating a predetermined quantity of oil on said hearth before flowto said shut-off mechanism occurs.

3. The liquid fuel burning apparatus defined in claim 2, wherein saidhearth, between said recess and said outlet port, is provided with asubstantially continuous sharp edge so located as to cause theaccumulating liquid fuel to build up to a predetermined depth above thelevel of said outlet port before discharging from said recess into saidoutlet port.

4. In a liquid fuel burning apparatus having means defining a combustionchamber; a centrally apertured refractory hearth in said combustionchamber and having a fuel atomizing and vaporizlng wall located adjacentits periphery against which oil and air are adapted to be projected by adistributing device located in the aperture in said hearth; said-hearthhaving a plurality of substantially continuous upper surface recessestherein located one inside the other; and means dening a discharge portopening into the upper surface of the hearth inside the innermost ofsaid recesses, and said port having its upper edge at a higher levelthan the bottoms of said recesses.

5. In a liquid fuel burning apparatus having walls defining a combustionchamber, a hearth supported in said combustion chamber; a fuel atomizingand vaporizing wall extending around the periphery of said hearth andspaced from the interior of said combustion chamber and adapted to haveliquid fuel and air projected toward it for combustion adjacent theupper edge thereof; an annular shield ring supported on said hearth inoutwardly spaced and surrounding relation to said wall and extending asubstantial distance above the top of said wall; and a at narrow grillstructure disposed within the confines of said shield ring comprising anannular member having a plurality of trough elements radiating outwardlytherefrom, said trough elements resting on said wall to support saidgrill structure in the apparatus.

6. In a liquid fuel burner assembly adapted to be installed in acombustion chamber, a closure for the lower end of said chambersubstantially centrally apertured to accommodate a rotatable fueldistribution head, a hearth mounted on said closure in surroundingrelation to said head and having an annular upper surface slopingradially in opposite directions from its inner and outer peripheries,means defining a drain outlet port in said hearth at the lowermostregion of said surface so that unburned liquid fuel deposited on saidsurface will drain toward said port, an annular ame rim surrounding saidhead mounted on said hearth in spaced relation to said head, an outerperipheral ange on said hearth spaced from said flame rim but within theconnes of said combustion chamber, and an'annular shield ring secured t0Said flange and upwardly into the combustion chamber. v,

mounted `on said hearth surrounding the aperture in said hearth andadapted to be impacted -b'y liquid fuel projected outwardly by arotating fuel distributing head extending upwardly throughthe apertureinsaid hearth, means proi viding a d rai'nport on, one side of saidhearth,

,means mounting said hearth in said chamber in suchinclined. relationtothe horizontal that liquid. fueldepozsited onA thehupper surface ofsaid hearth will drain .therealong toward said port, and areces'sedhearth region about said drain port in the path' of liquid fuel. tendingto drain into said port for accumulating .a predetermined sinall amountof it on the hearth surface before allowing .any ofhit to, enter saidport, but overowing: into'saidpot when an excess ofvfluidfelfainshsrsintoff 9.- Inthe liquid f uel burning apparatus denedclainifus'aid discharge V port being located tolviladthe.outer pai-tofsaid hearth, and means saidglhearth'linsuch inclined relation as to',cause ,liquidfuel to drain along said hearth 10a ,1n a burningapparatus,a, hearth apeitured .toaccommodatea Afuel projecting head 'and having a'low levl region toward which the upper surfac'- f said h" h1, slopes',said .low level region being formed vfllth a drain outlet port adaptedto .be.' .coupled to V1a. burner -shut-ofi? vde- Vice, and a recessedhearth' region, about said drain outlet port ifi' the path f liquidfuel' tending to drainalong said. surface into said port foraccumulating'r ,a predetrmined`-small amount of said liquid fueIHbefore'allowing any of itto enter4 said port, butoyerowin'g into Savidport whenan excess of.,liduid fuel drains thereinto, said accumulatedl'iqiiid fuel in, A'Said means being exposed to .vaporizing heat and tending toburn off during normal operation of ,said apparatus.

MiLfroN A,A POWERS.. NOEL` HQ SUTTERFIELD.

REFERENCES CITED The following references are of record in the le ofthis patenti' UNITED STATS PATENTS Number ,Nfaie Date 1,886,675Heathf..z Nov. 8, 1932 2,013,642 Binkly sept. 1o, 1935 2,029,859 o0zz1Een .4, 1936 2,034,737 Appel' Mr. 24, 193,6 2,051,130 Cole Aug. 18,193.6 2,064,080 Powers Dec. 15, 1936 2,094,764 Wi1SQn.'. f Q` L Oct. 5,193.7 2,102,763 Suttereld Dec. 21, 193.7 2,104,691 Q01e,; ,qan. 4., 19382,117,781 Wilson Q May 17, 1938 2,130,471 Powersfn-.. Sept. 20, 19382,161,220 BeckettA June s, 1939 2,207,002 D 'L ".Q July 9, 1940

